title: Calmodulin-dependent spectrin kinase activity in resealed human erythrocyte ghosts.
abstract: Membrane protein phosphorylation has been studied in resealed human erythrocyte ghosts by measuring the incorporation of 32P into spectrin and band 3. Norepinephrine- and Ca2+-stimulated phosphate incorporation was diminished in ghosts depleted of calmodulin. Ghosts prepared with endogenous calmodulin showed Ca2+- and norepinephrine-stimulated protein phosphorylation only when the ghosts had been resealed in the presence of (gamma-32P)ATP. Ghosts resealed with or without calmodulin in the presence of unlabeled ATP showed no net gain or loss of 32P when exposed to norepinephrine or a Ca2+-specific ionophore. These observations suggest that Ca2+ and norepinephrine stimulation of membrane protein phosphorylation is mediated by calmodulin-dependent spectrin kinase activity, and not by increased turnover of spectrin ATPase or by inhibition of phosphospectrin phosphatase.
mesh_terms: D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D002135:Calcium-Binding Proteins / Q000097:blood*; D002147:Calmodulin / Q000097:blood*; D004910:Erythrocyte Membrane / Q000187:drug effects / Q000201:enzymology*; D004912:Erythrocytes / Q000201:enzymology*; D006801:Humans; D008565:Membrane Proteins / Q000097:blood; D009638:Norepinephrine / Q000494:pharmacology; D010750:Phosphoproteins / Q000097:blood; D010766:Phosphorylation; D011494:Protein Kinases / Q000097:blood*
chemical_list: D002135:Calcium-Binding Proteins; D002147:Calmodulin; D008565:Membrane Proteins; D010750:Phosphoproteins; D000001:Calcimycin; D011494:Protein Kinases; C033464:spectrin kinase; D002118:Calcium; D009638:Norepinephrine